Manufacture of soap



Nov. 3, 1942.

A. T. SCOTT ETAL MANUFACTURE OF SOAP Filed Nov. 4, 1941 2 Sheets-Sheet l PARTLY SPENT LYE ATER.

M UB1.

NEAT SOAP.

c E NTR FUGAL WI m A O .S CENTRIFUGAL |A|l|J,\ b n R 2 5 E E 1 m m M N E w w w m m N, O 5w ENTRIFUGAL l l E m a N NE w v L E u w 0 i m F A TTORNE Y 0 "LO 2 1 FROM T {9 xi 2 2, CENTR1FUGAL-46 moms HEAT SCAD ,soAp

AClD WATER.

M 1x511 l FROM TO- 19,20 x21 CENTRIFUGAL- 4s mares JPKI 3 c E MODIFYING NF AGENT NlGRE f 40 F U G A L MIXER.

IMPURI'HESQ- INVENTORS *flshconT Scott Nov. 3, 1942.

A. T. SCOTT ETAL 2,300,751 MANUFACTURE OF SOAP Filed Nov. 4, 1941 2 SheetsSh e'et 2 Leopold Sendgr BY M ATTORNEY Patented Nov. 3, 1942 MANUFACTURE OF SOAP I Ashton T. Scott, Ardmore, Pa., and Leopold Sender,

Sharples Corporation poration of Delaware Baltimore, Md.,' assignors to The Philadelphia, Pa., a cor- Application November 4, 1941, Serial No. 417,748

8 Claims. (01. 260-418) The present invention relates to the art of soap making, and was conceived primarily as a method of making soap continuously with the aid of centrifugal separators. Processes for the manufacture of soap by passing a saponifying reagent continuously into confluence with a source of fat, saponifying the fat by passage of the mixture at saponifying temperature continuously through mixing apparatus, and separating spent reagent from fat by centrifugation are described and claimed in the co-pending applications of.

Ashton T. Scott, Serial No. 333,547, filed May 6, 1940, and Serial No. 334,297, filed May 10, 1940. The present invention is primarily a development of the procedure of these two co-pending applications resulting in improved mixing of reagent with the source of fat and improved yield of soap,

by which these results may be obtained without taining mass is maintained under intensive agitation practically up to the moment when it is passed into a centrifugal separator for removing the aqueous reagent phase from the soap. The. 'saporiification ispreferably accomplished in a plurality of counter-current stages, and the removal of the soap from the zone of centrifugation is accomplished by mixing water or saponifying reagent with the soap while it is still in a turbulent condition due to discharge from the zone of centrifugation. The soap is grained, and thus conditioned for removal of the aqueous phase, prior to centrifugation, by the addition of a salt solution, or an excess of saponifying reagent which serves as a salting out agent. In the process of application Serial No. 334,297, the salting out operation is accomplished. simultaneously with the saponification by addition of the salting out agent before the start of the saponification reaction.

At the conclusion of the final saponification step of the above-mentioned Scott applications, the soap from the centrifugal of the last saponification stage is mixed with water, and also with electrolyte if necessary, to change the grained or curd soap to a neat soap and at-the same time form a new phase which is known as nigre. The

neatsoap and nigre are thereafter separated from each other by centrifugation.

By the practice of the present invention, the economics of the Scott process are improved by returning the nigre from the centrifugal by which it is separated from neat soap to one of the saponification stages of the process. By operating in this manner, the nigre, which contains a large proportion of soap, serves to emulsify the saponifying reagent with the source of fat to be saponified, thereby improving the contact between reagent and fat and speeding up the saponi-fication reaction. At the same time, the soap contained in the nigre is recovered from the saponified mass in one of the centrifugals by which the aqueous reagent phase is separated from soap in the cycle of mixing and centrifugal separating steps constituting the saponification stages of the soap making operation.

In accordance with modifications or amplifications of the above procedure, the invention may be practiced by separating dirt from the nigre and neat soap as a third efiiuent in the fitting operation by which the nigre is separated from theneat soap. The separate removal of dirt in this manner effects a still further improvement in the process, since, after separation of dirt, the nigre may be returned to one of the earlier saponification stages and combined with further fat and alkali with a minimum of contamination by dirt from the preceding saponified mass which Figure 1 represents a simple form in which the invention may be practiced,

Figure 2 illustrates a slight modification oramplification of the process of Figure l, and

Figure 3 represents a further modification or amplification.

In the practice of the invention as illustrated in Figure L'fat from container I0 is passed into confluence with a saponifying reagent, such as lye from container l I. The fat and lye are passed together, preferably under super-atmospheric pressure, through a mixer l2, which is heated to a temperature (e. g., 200 F.) sufiiciently high to efi'ect saponification of most of the fat during pamage through the mixer. The mixture is maintained in a state of intensive agitation in order to insure rapid saponification of the fat, and fluidity of the mixture until it is passed into centrifugal i3. The soap is grained prior to passage to the centrifugal Hi, this graining being accomplished either by adding a graining agent in a separate step to the substantially saponified mass, as in Scott application Serial No. 333,547, or by adding a graining agent to the mixture before saponification commences, as in Scott application Serial No. 334,297. In either case, an aqueous saponifying reagent phase, which may be spent lye containing impurities removed from the partially saponified mass, is removed continuously as one eflluen-t from the centrifugal l3, and grained soap, containing a small proportion of unsaponified fat, is removed as a second eflluent from that centrifugal.-

I'he grained soap from centrifugal I3 is continuously mixed with a further quantity of saponifying reagent, preferably by injection of the saponifying reagent directly to the cover of the centrifugal in order to assist in discharge of the grained soap from the centrifugal and intimately mix the saponifying reagent therewith while the soap is in a turbulent condition due to discharge from the centrifugal. In any case, the mixture of grained soap and residual unsaponified fat with fresh saponifying reagent is passed through a mixer 15 and subjected to saponifying and graining steps prior to passage to a second centrifugal l6, which effects separation between partly spent lye and grained soap similar to the separation effected in the centrifugal Hi.

The grained soap discharged from centrifugal l6 may next be mixed with water from container I! in mixer 21, this water being added in suflicient skilled in the art.

The steps discussed above in connection with the elements. In to l8 of the flow sheet are disclosed in the co-pending applications of Ash'ton T; Scott which have been discussed. In the practice of the present invention, nigre from centrifugal I8 is returned from that centrifugal to one of the saponiflcation stages involved in treatment of further quantities of fat with saponifying reagent. Since this nigre is derived from a centrifugal treatment involving application of a force many thousand times the force of gravity in centrifugal l8, a large part of the dirt will ordinarily be separated from the nigre as well as the neat soap in this centrifugal treatment. thereby providing a nigre which isof considerably higher quality than the nigres obtained by the kettle soap making process. In view of this fact, the nigre may be returned to one of the saponiflcation stages over a prolonged cycle of operation in the practice of the process, without becoming other impurities may be best separated from the p be practiced by returning the nigre into the saponiflcation cycle prior to the practice of the first saponiflcation step, as indicated by the reference character I9, or it may be returned prior to the second saponification step as indicated by the reference character 20. The point at which the nigre is returned to the saponification cycle will depend largely upon the manner in which the .saponification steps are conducted, upon the concentration of the reagent used in these steps, for example. vA .part of the nigre may be returned at point l9, and another part at point 20, as indicated by the flow sheet of Figure 1. As a still further alternative, a part, or all, of the nigre sapbnifying reagent with fat, but the advantages of the invention may be partially attained, insofar as recovery of soap values is concerned, even by return of the nigre at point 22; i. e., to a point in the cycle of operations subsequent to completion of the entire saponi-fication reaction.

Figure 2 illustrates an operation in which a centrifugal 30 provided with special discharge outlets for separated dirt is substituted for the centrifugal Hi. In the practice of the embodiment of the invention illustrated in this figure the impurities separated from the nigre are discharged through special outlets extending from. the inner circumferential wall of the rotor, while the nigre and neat soap are continuously dis-' charged separately from these impurities and from each other. In this embodiment of the invention, as in the embodiment of Figure 1, the nigre may be returned to the saponiflcation cycle at the points I9, 20 or 22 or separate parts of it may be returned at all three of these points.

or any two of them. In removal ofimpurities from the nigre and neat soap, if the soap-containing mixture being subjected to the fitting operation contains a substantial amount of free alkali, it will be desirable to add a source' of organic or inorganic acid, in order to neutralize a part or all of the free alkali, since the dirt and nigre when it is in a substantially neutral condition, or-contains at most only a very small amount of free alkali. A feature of the invention therefore consists in addition of a source of acid, which may be an organic or inorganic acid or an ester (e. g., a saponiflable fat) fromcontainer 3|, and heating of the mixture after addition of, this source of acid in the mixer 2| in order to assist in neutralization of free alkali and thereby convert the nigre into a condition in which a large proportion of the dirt may be sep-. aratedfrom it in the centrifugal 30 or the centrifugal l8. While this feature of addition of a source of acid is particularly valuable in connection with the practice of the process in cases in which the nigre is recycled to one of the saponification stages, it has value as a step for proof a source of acid in performance of the centrifare pracbe passed through a centrifugal 40 which serves to clarify the nigre further -by removal of dirt and other impurities therefrom, and the clarified nigre may then be returned to the saponification cycle as discussed above. In case such a separate clarifying step is performed upon the nigre before recycling it, a modifying agent, which may be water or a source .of acid as discussed above, is preferably added to the nigre before it is passed to the centrifugal 40. The dilution of the nigre with water frees a part of the impurities remaining in the nigre after discharge from the centrifugal l8 or 30, and these impurities may then be removed by passage of the nigre through the centrifugal 40. In case this separate clarifying step is performed, the preferred procedure involves mixing a source of acid with the nigre in the mixer 4| by passing such source of acid from container 42 into confluence with the nigre, and heating the mixture to facilitate neutralization or partial neutralization of free alkali by the source less of whether water or a source of acid be used as the agent to assist in the centrifugal clarification of the nigre by the centrifugal force, however, the addition of a modifying agent and performance of a separate step of centrifugal clarification of. the nigre is valuable in the practice of the present invention, since it enables us to recycle the nigre with a minimum of contamination source of fat with a further quantity of saponifying reagent in the manufacture of a further quantity of soap.

2. In the manufacture 'of soap, a process comprising accomplishing a saponifying stage by mixing a source of fat with a saponifying reagent, subjecting the resulting mixture to saponifying reaction conditions, salting. out the soap to produce a soap phase and an aqueous phase. and thereafter subjecting the resulting mixture to centrifugation to separate the soap phase from aqueous phase as the final step of said saponifying stage, thereafter mixing the grained soap and unsaponified fat derived from said saponifying stage with a further quantity of saponifying reagent and subjecting the resulting mixture to a second saponifying stage including the same steps as said first-mentioned saponifying stage,

thereafter fitting the grained soap derived from said second-mentioned saponifying stage by mixing said grained soap with water and separating prising accomplishing a saponifying stage by mixing a source of fat wtih a saponifying reagent, subjecting theresulting mixture to saponifying reaction conditions, salting out the soap to produce a soapphase and an aqueous phase, and thereafter subjecting theresulting mixture to centrifugation to separatethe soap phase from aqueous phase as the final step of said saponifying stage, thereafter mixing the grained soap and unsaponified fat derived from said saponifying stage with a further quantity of saponifying reagentand subjecting the resulting mixture to a of the soap-containing mass with which it is mixed in the recycling operation.

Various modifications will be obvious to those skilled in the art, and we do not therefore wish to be limited except by the'scope of the following claims.

We claim:

1. In the manufacture of soap, a process comprising accomplishing a saponifying stage by mixing a source of fat with a saponifying reagent,

subjecting the resulting mixture to saponifying reaction conditions, salting out the'soapto produce a soap phase and an aqueous phase, and thereafter subjecting the resulting mixture to centrifugation to separate the soap phase from aqueous phase as the final step of said saponifying stage, thereafter mixing the grained soap and unsaponified fat derived from said saponifying stage with a further quantity of saponifying resecond saponifying stage including the same steps as said first-mentioned saponifying stage, thereafter fitting the grained soap derived from said second-mentioned saponifying stage by mixing said grained soap with-water and separating nigre from neat soap by centrifugation, and returning nigre derived from said last-mentioned centrifugation to the second-mentioned saponi fying stage at a point in the cycle of operations subsequent to the saponifying reaction of said second-mentioned saponifying stage in treatment of a further quantity. of a source of fat with a further quantity of saponifying reagent in the manufacture of a further quantity of soap.

4. In the manufacture of soap, a process comprising accomplishing a saponifying stage by mixing a source of fat with a saponifying reagent, subjecting the resulting mixture to saponifying reaction conditions, salting out the soap to produce a soap phase and an aqueous phase,

and thereafter subjecting the resulting mixturesecond saponifying stage including the same steps as said first-mentioned saponifying stage,

thereafter fitting the grained soap derived from I said second-mentioned saponifying stage by mixing said grained soap with water and separating nigre from neat soap by centrifugation, and re turning nigre derived from said last-mentioned centrifugation to the first-mentioned saponifying stage at a point in the cycle of operations prior 4 to the saponifying reaction of said first-mentioned saponifying stage in treatment of a further quantity of a source of fat with a further quantity of saponifying reagent in the manufacture of a further quantity of soap.

5. In the manufacture of soap, a process comprising accomplishing a saponifying stage by mixing a source of fat with a saponifying reagent, subjecting the resulting mixture to saponifying reaction conditions, salting out the soap to produce a soap phase and an aqueous phase, and thereafter subjecting the resulting mixture to centrifugation to separate the soap phase from aqueous phase as the final step of said saponifying stage, thereafter mixing the grained soap and unsaponified fat derived from said saponifying.

stage with a further quantity of saponifying reagent and subjecting the resulting mixture to a second saponifying stage including the same steps as said first-mentioned saponifying stage, thereafter fitting the grained soap derived from said second-mentioned saponifying stage by mixing said grained soap with water and separating nigre from neat soap by centrifugation, and returning nigre derived from said last-mentioned centrifugation to the second-mentioned saponifying stage at a point in the cycle of operations prior to the saponfying reaction of said secondmentioned saponifying stage in treatment'of-a further quantity of a source of fat with a further quantity of saponifying reagent in the manufacture of a further quantity of soap.

6. In the manufacture of soap, a process-comprising accomplishing a saponifying stage by mixing a source of fat with a saponifying reagent,

subjecting the resulting mixture to saponifying reaction conditions, salting out the soap to produce a soap phase and an aqueous phase, and thereafter subjecting the resulting mixture to cntrifugation to separate the soap phase from aqueous phase as the final step of'said saponifying stage, thereafter fitting grained soap derived from the saponifying reaction by mixing said grained soap with water and with asource of acid and neutralizing free alkali of the mixture by ing stage, thereafter fitting grained soap derived from the saponifying reaction by mixing said grained soap with water and separating nigre from neat soap by centrifugation, thereafter adding water to the nigre and separating impurities from the nigre obtained by said last-mentioned step ofcentrifugation by a subsequent step of centrifugation, and returning nigre derived from said final step of centrifugation' to a saponifying stage in treatment of a further quantity of a source of fat with a further quantity of saponifying reagent in the manufacture of a further quantity of soap,

8. In the manufacture of soap, a-process comprising accomplishing a saponifying stage by mixing a source of fat with a saponifying reagent, subjecting the resulting mixture tosaponifying reaction conditions, saltin out the soap'toiproduce a soap phase and an aqueous phase, and thereafter subjecting the resulting mixture to centrifugation to separate the soap phase from aqueous phase as the final step of said saponifying stage, thereafter fitting grained soap derived from the saponifying reaction by mixing said grained soap with water and separating nigre from neatsoap by centrifugation, thereafter adding a source of .acid to the nigre and neutralizing free alkali of the mixture by said source of acid and thereafter separating impurities from the nigre obtained by said last-mentioned step of centrifugation by a subsequent step of centrifugation, and returning nigre derived from said final step of centrifug'ation to a saponifying stage in treatment of a further quantity of a source of fat with a further quantity of saponifying reagent in the manufacture'of a further quantity 

